Chimney cap



Sept. 19, 1950 w. c. COLEMAN CHIMNEY CAP 2 Sheets-Sheet 1 Filed Feb. 17, 1947 (Ittomegs Sept. 19, 1950 w. c. COLEMAN CHIMNEY CAP Filed Feb. 17, 1947 2 Sheets-Sheet 2 Zhwcntor W////om C (o/emu.

Way" WM.

(Ittornegs i This invention relates j leeward side.

; downdrafts or increase, in

Patented Sept. 1 1950 llVilliam 0. Coleman, Wichita, Kans., assignor to The Coleman Company, Inc., Wichita, Kans., a

corporation of Kansas Application February 17 1947, Serial No. 729,032

to chimney or vent caps particularly for discharging products of combustion resulting in fuel burning'appliances. It is well known that air currents blowing across a chimney often produce downdrafts which interfere with proper burning of fuels in various appliances that may be connected with a chimney and toovercome this difficulty, it is the practice to provide the chimney with various forms of caps havingoutlet for products of combustion on the Such caps reduce interference by downdrafts but they result in an increase of draft when the wind is blowing since they create a low pressure area on the leeward side that increases draft through the chimney.

Efiicient operation offuelburning appliances and especially those utilizing liquid and gas fuels requires a uniformly constantdraft or pressure differential to supply the amount of air for proper burning of the fuel and to prevent: heat waste up the chimney or vent to which the appliances are connected.

Various draft meters or regulators have been devised for automatic regulation of the draft or pressure differential and many of these devices are'capable of closely controlling the draft but the best of them cannot perform satisfactorily under draft caused by external air currents; I z l f Therefore, it is the purposeaof the 'present invention to provide a chimney or ventcap which results in a constantly uniform draft regardless of the exterior wind conditions so as to effect a uniform measured flow of air to the fuel burning appliance as set by a draft meter or regulator.

Another object of the present invention is to provide a ventcap structurewhich, affects circumvolution of the chimneygases anddisturbing wind currents in such manner as to create resistance to discharge thereof which is 'sufiicient for counteracting the effect oflow; pressure area on the leeward side of the chimney.

Further objects of the invention are to provide a vent cap structure which excludes disturbing wind currents from thechimneyorvent to which .it is connected; to provide awflue cap of simple and inexpensive construction; and to provide a chimney cap which is not objectionable in appearance when mounted on a chimneyor other cap showing the manner. of mountingithe cap on a chimney top or ventduct.

5 Claims. (01. 98-66) Fig. 3 is a horizontal section through the cap on the line 3-4 of Fig. 1.

which includes an inner tubular member having a cylindrical wall 2 that may be formed of a strip of sheet metal rolled into cylindrical shape and the ends 3 and 4 of the strip overlap and are secured in any suitable manner such as spot weldmg. To facilitate mounting of the cap the seam at the lower end of the cylindrical wall is preferably left in loose condition so that the wall may be readily contracted about the neck 5 of a chimney top by means of a bolt 6. The bolt 6 passes through ears 1 and 8 that are secured as at 9 to the wall 2 on opposite sides of the seam at points immediately above the lower edge of the wall. The upper end of the wall 2 is closed by a top or cover In of substantially dome shape and includes an annular flange l I that is sleeved over the wall 2 and secured, for example, by spot welding the flange to the wall.

Formed in the wall 2 is a plurality of elongated openings l2 that are arranged substantially parallel with the axis of the cap and are spaced apart in an annular series. The openings are provided by slitting the metal of the strip transversely at spaced points and ends of the slits diverge laterally to provide vanes I3 that are struck outwardly to extend in chordal planes passing through the cylindrical wall in offset relation from the axis of the cylinder, all of the vanes being bent at substantially the same angle and the same direction about the circumference of the wall. The vanes thus formed have vertical edges l4 extending parallel with and spaced from the vertical edges P5 of the openings l2 to provide spaces l6 through which gases diverted by the vanes are caused to move circumferentially of the wall. The lower ends of the openings I2 are preferably spaced above the contract/able end of the cylinder to provide the collar by which the cap may be mounted on the neck 5 of the chimney topping and to mount an annular ring I! having an inner flange 13 attached to the wall 2 adjacent the lower edges of the openings I2 and carrying an outwardly and upwardly extending annular web 19 terminating in an upstanding flange 20. The web portion IQ of the ring I8 has a circular series of openings 2| for a purpose later described. The flange 20 encircles an outer tubular member having a cylindrical wall 22 which cooperates with the inner wall to provide an annular passageway 23 therebetween and through which vented gases and disturbing air currents are caused to move in circumvolution as later described. The outer wall is also formed of a strip of sheet metal rolled to shape and having the ends thereof overlapped as at'24 and secured together by suitable fastening means such as one or more rivets 25 or the wall may also be spot welded in the manner of the inner wall. The lower edge of the outer wall seats within the flange 20 and projects above the inner wall to carry a ring-like top 26 that is spaced above the dome portion of the top Ill toform an upward and inward continuation of the annular passageway. The top 26 has an annular flange 27 that sleeves over the upper edge of the outer wall and the body or web portion 28 of the ring curves inwardly and upwardly over the dome portion of the inner top to terminate in an axial outlet opening 29. The marginal portion of the top surrounding the opening 29 may be reinforced by an annular rib 30.

The outer wall 22 is likewise provided with a plurality of circumferentially spaced elongated openings 3| extending from the flange 20 to the flange 21 and which are formed by providing the metal with a plurality of parallel slits having lateral terminals and striking the metal inwardly to produce a plurality of inwardly extending vanes 32 which project within the annular passageway 23 and are angular-1y disposed in the direction of travel assumed by the vented gases. The disturbing wind currents are therefore directed circumferentially of the passageway in circumvolution about th vented gases. The outer wall 22 is preferably removable'from the flange 2G and it is, therefore, secured thereto by fastening devices such as metal screws 33 that are inserted at a plurality of points about the circumference of the flange 20 The top ring 26, however, may be permanently attached to the upper edge of the outer wall 22'by welding or the like.

In assembling the cap, the ring I! is sleeved over the wall 2 and secured in position thereon, for example,'by spot welding. The dome-shaped top H) is then sleeved on the upper end of the wall and secured in suitable manner so that it encloses the upper end of the vent duct to which the device is associated for diverting the gases outwardly through the slot-like openings [2 as later described.

The annular wall 22 of the outer member is inserted within the flange 21 of the top ring 26 and the flange secured thereto, for example, by spot welds. The wall 22 of the outer member is then passed over the inner member so that the lower edge thereof seats within the flange 20. The fastening devices 33 are then inserted to complete the assembly.

In applying the device, the collar portion of the inner member is sleeved over the vent pipe or neck portion of the chimney top after which the bolt 6 is tightened.

In operation, the wind currents moving over the chimney cap pass through the slot-like openings 3! in the windward side of the outer wall and are directed by the vanes 32 into circumvolution about the annular passageway 23 as shown by the arrows in Fig. 5. The change of direction of the air currents and centrifugal motion of the circumvolved streams of air prevent entrance of the air into the inner member of the cap. The air currents will thus travel through the passage- 4 way to the leeward side of the cap and escape through the openings. In escaping from the cap the air currents must change direction (Fig. 6) and this change in direction produces resistance to flow sufficient to counteract the effect of the low pressure area on the leeward side of the cap. The flow to the low pressure area is thus retarded so as to prevent increase in draft through the chimney. The air currents which do not escape will continue to circumvolve about the passageway and will rise upwardly across the dome l0 and be discharged axially of the cap through the outlet opening 29. Simultaneously the gases vented through the chimney are diverted laterally through the slot-like openings l2 by the vanes l3 to move in circumvolution about the inner side of the passageway in the same direction as the disturbing air currents. The gases are thus discharged with the air flow so that the products of combustion are not affected by the low pressure area. Consequently flow of gases through the chimney remain at constant velocity regardless of the external wind conditions. The openings 2| at the lower end of the annular passageway provide for equalization of pressures in the passageway and in some instances provide outlet for disturbing air currents that may tend to move downwardly through the slot-like openings of the outer member. Should air currents move downwardly across the top of the ring 26 and through the opening formed thereby, they are diverted by the dome-shaped top Ill and cannot enter the inner member to produce downdrafts.

On calm days when no wind is blowing the gases merely pass from the chimney and seek outlet through any of the cap openings.

From the foregoing it is obvious that I have provided a chimney cap that is of simple and inexpensive construction and which is adapted to divert and dispose of disturbing air currents that ordinarily cause change in draft which interferes with satisfactor operation of draft meters or draft regulators.

It is obvious that with a satisfactory draft regulator to establish a predetermined uniform flow of combustion supporting air to the burner essential to highest efficiency, the chimney cap constructed in accordance with the present invention makes it possible to maintain the same draft on windy days as maintained on calm days.

'What I claim and desire to secure by Letters Patent is:

1. A vent cap including an inner member adapted for forming a terminal of a vent duct and having an annular wall provided with a series of outlet openings, a dome-shaped top carried by said wall for diverting gases through said openings, means associated with said openings for directing the gases in circumvolution about said Wall, an outer member having a cylindrical wall spaced from the wall of the inner member for forming an annular passageway for the circumvolved gases and having an annular series of openings for admitting exterior air currents into said passageway from the windward side and discharging the air currents and gases from the leeward side when the device is in use, means associated with the last named openings for directing the air currents in concurrent circumvolution with the gas and effecting change in direction of the air and gases seeking outlet on the leeward side, a ring member carried by the outer wall and extending upwardly and inwardly over the domeshaped top for forming a substantially axial outlet for said eircumvolved air and gas that does not ried by said wall for diverting gases through said openings, means associated with said. openings for directing the gases in circumvolution about said wall, an outer member having a cylindrical wall spaced from the wall of the inner member for forming an annular passageway for the circumvolved gases and having an annular series of openings for admitting exterior air currents into said passageway, means associated with the last named openings for directing the air currents in concurrent circumvolution with the gas, a ring member carried by the outer wall and extending upwardly and inwardly over the dome-shaped top for forming an axial outlet for said circumvolved air and gas above said. top, and a ringlike support carried by one of the walls for supporting the other wall and having openings into said passageway for effecting equalization of pressures in the passageway.

3. A device adapted for venting gases from the terminal of a vent duct without interference by external air currents including an inner member having a cylindrical wall adapted to form the terminal of the vent duct and having an annular series of vertically positioned outlet openings for gases passing through said duct with one opening spaced from the adjacent openings, a gasdeflecting vane projecting outwardly from a vertical side of each of said openings and angularly across said openings for directing the gases in circumvolution around the inner member, an outer member having a cylindrical wall spaced from the cylindrical wall of the inner member to form an annular passage-way therebetween and in which the gases are circumvolved, said wall of the outer member having a similarly arranged annular series of openings for passing interfering air currents into said passageways, a vane extending inwardly from a vertical edge of each last named openings and into the passageway for affecting circumvolution of disturbing air currents in said passageway in the same direction as the circumvolved gases, a closure member extending over said passageway to divert gase rising in said passageway toward the axis of said members and having an outlet in the axial direction of said members, and a ring member fixed to and encircling the inner member below the openings in said members and forming a support for the outer member, said ring member having openings below said vanes for draining off any rain water intercepted by and running down the vanes.

4. A chimney cap including inner and outer cylindrical members having walls spaced apart to provide an annular passageway, said walls having a series of slot-like openings for admitting gases from the inner member and external air gas and air currents in said concurrent flow from the entrance side of said air currents and for changing direction of said flow on discharge through the slot-like outlets at the opposite side, a ring-shaped member having a peripheral flange sleeved over the upper end of the outer member and forming an annular outlet opening for gas.

and air currents which do not escape through said slot-like openings, a dome-shaped cover having a flange sleeved over the inner member to assure diversion of gas through said slot-like openings of the inner member and to divert an air currents that maytend to move downwardly through said outlet opening, a collar encircling the opposite end of the inner member and having a peripheral flange sleeved over the lower end of the outer member to support the outer member and having an inner flange fixed to said inner member, said collar having openings through which pressure is equalized in said passageway.

5. A chimney cap including inner and outer cylindrical members having walls spaced apart to provide an annular passageway, said walls having a series of slot-like openings for admitting gases from the inner member and external air currents from outside the outer member into said passageway for concurrent flow in said passageway, vanes extending into the passageway from edgesof the slot-like openings and sloping in the direction of said concurrent flow to direct said gas and air currents in said concurrent flow from the entrance side of said air currents and for changing direction of said flow on discharge through the slot-like outlets at the opposite side, a ring-shaped member having a peripheral flange sleeved over the upper end of the outer member and forming an annular outlet opening for gas and air currents which do not escape through said slot-like openings, a dome-shaped cover having a flange sleeved over the inner member to assure diversion of gas through said slot-like openings, a dome-shaped cover having :a flange sleeved over the inner member to assure diversion of gas through said slot-like openings of the inner member and to divert any air currents that may tend to move downwardly through said outlet opening, a collar encircling the opposite end of the inner member and having a peripheral flange sleeved over the lower end of the outer member to support the outer member and having an inner flange fixed to said inner member, said collar having openings through which pressure is equalized in said passageway, and clamping means on the inner member for contracting within a member about a vent on which said chimney cap is to be mounted.

WILLIAM C. COLEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain A. D. 1913 

